Measures reported by OraRacRollbackTest
The immediate availability of rollback segments for the various activities that occur in a database server is very critical. Contention for rollback segments can adversely impact the performance of a database server and hence, needs to be detected and reported immediately. To detect contention for rollback segments on each node in an Oracle cluster, the OraRacRollbackTest test monitors every cluster node for the degree of contention for buffers that contain rollback segment blocks.
Outputs of the test : One set of results for every cluster node monitored
The measures made by this test are as follows:
| Measurement |
Description |
Measurement Unit |
Interpretation |
| Pct_system_segment_waits |
Denotes the ratio of the number of waits for acquiring a header block or a block of the SYSTEM rollback segment to the total number of requests for data to this cluster node, measured over a period of time. |
Percent |
If the number of waits for any class of block exceeds 1% of the total number of requests, the size of the SYSTEM rollback segment needs to be increased. |
| Pct_non_sys_segment_wait |
Denotes the ratio of the number of waits for acquiring a header block or any other block of a non-SYSTEM rollback segment to the total number of requests for data to this cluster node, measured over a period of time. |
Percent |
If the number of waits for any class of block exceeds 1% of the total number of requests, the sizes of the existing rollback segments may need to be increased. Alternatively, additional rollback segments to may be created to reduce contention. |
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